Socket



Feb. 27, 1934- N. c. SCHELLENGER SOCKET Filed Feb. 23, 1929 I yer." M MM @4293.

" Patented Feb. 27, 1934 UNITED STATES PATENT OFFICE SOCKET Newton C. Schellenger, Elkhart, Ind, assignor to Chicago Telephone Supply Company, Elkhart, Ind., a. corporation of Delaware Application February 23.1929; Serial No; 341,945

8 Claims.

mine the position of the tube in its socket. Thatis, the socket which is to receive the tube is equipped with but two holes of suificiently large diameter to receive the large prongs of the tube. Therefore, the tube can be placed in the socket in but one position, that being the position in which it is intended to go.

Plug-in coils or inductances for radio. sets are provided with prongs of such dimensions and so spaced as to correspond to vacuum tubes, so that the coils may be pluggedinto standard sockets. The spacing and diameter variations of the prongs insure that the coil will be placed in the socket properly; that is, it will establish proper connections with the socket.

Sockets of this kind comprise a substantially smooth base, in which are placed the four or five holes through which the prongs are to project.

In order to insert the tube or coil in the socket,

it is necessary to bring its large prongs into registration with the large diameter holes in the.sock-' If the socket is located so that there is very et. little waste space around it, it is difiicult to bring the prongs into registration with the proper holes.

To overcome this difliculty, I have provided an improved socket in which I have placed a guide plate over the surface of 'the usual tube socket. In this plate, I have cut a circular hole, the pe ripheryof which accurately aligns with the out- 40 side edges of the holes through which the prongs are to project. In inserting a tube or coil into this improved socket, the prongs are brought into registration with the large hole without especial difiiculty, and are turned in this hole until the prongs register properly with the holes through which they are to project. The edges of the prongs bear against the edge of the hole in the guide plate, which thereby serves as a guide to assist in locating the relatively small holes through which the prongs must project.

Preferably, this guide plate is made of an insulating material, ,such as Bakelite or Micarta I plate, although hard rubber or fibre may be used.

-Vacuum tubes of the modern type are provided, with relatively long prongs, which. are

brought into tangential contact with a metallic spring, through which contact the electrical circuits are carried to the tube. Plug-in coils follow these tube dimensions closely. In order to insure a good electrical contact, the contacting members are made of spring material and are tensioned to press firmly against the prongs. This tensioning of the contacts causes them to bear against the prongs at an angle, and the spring tension on the prongs at this angle tends to force the prongs up out of the socket. In the so-called alternating current sets, and particularly in the so-called B battery eliminator or power packs for such sets, considerable trouble has been experienced in the tubes actually jumping out of their sockets.

A further object of my invention is to provide an improved contact for making connection with the cylindrical or rod-like studs of a vacuum tube or the like. In the preferred form of my inven- 7 tion this comprises a fiat spring member extending, when uni -ressed, into the path of the prong or stud as it is inserted endwise and having a slot with substantially parallel edges extending lengthwise so that the prong, as it' is guided. into 89 place, pushes the spring aside to stress the same. The spring is thus pushed back and stressed and then presents the edges of the slots along two substantially parallel lines on the longitudinal surface of the cylindrical stud or prong. The 35 endwise movement-of'the prong or stud causes a highly beneficial clearing or scouring effect along these lines of contact, due to the limited area of engagement which the edges of the thin sheet metal of the spring have upon the surface of the 90 stud. The outer end of the spring is preferablyv bent back to avoid engagement with the outer end of the prong when it is fully inserted, to avoid interference with the contact by a drop or film of solder whichmay be formed upon the outer end of the prong. In the form herein shown the edges of the slots are beveled, but. this is not an indispensable feature of the invention. The real virtue, as has been amply demonstrated by commercial test, is the high unit pressures which are secured along lines extending in the "direction of insertion or removal of the stud by presentation of .the edges of the metal in two lines of contact along the stud and also the centering or clutching action which the edges of the I y assembled socket;

-.of one of the contact springs. i

By referring to Figures 14, it will be seen that the socket comprises the insulating base 2 which is preferably a substantially circular plate with extending mounting ears, to which plate are attached the contact springs 8 and 9, there being two of each of these springs. Contact springs 8 '.are provided with a narrow slot 1 0, which, is

adapted to engage the small diameter prongsof a vacuum tube or plug-in coil. Contact strips 9- are provided with a larger slot 11, whichis adapted to engage the large diameter prongs of the tube or coil. The edges of the slot are held against spreading by the transverse connecting portion or web remote from the base and clear of the prong when the same is inserted. These contacting strips are held onto the base 2 by means of rivet 12, which may be either a solid rivet or preferably an eyelet, as shown. Each contacting strip is equipped with an integral projection or car 14, which registers with a hole in the base 2 to lock the contacting strip against rotation around the rivet as a center.

The base 2 is provided with accurately spaced holes 3 of proper diameter to receive the small sized prongs of a vacuum tube or a coil, through which hole these prongs project into contact with the springs 8, which are mounted below the base.

The base is also provided with larger diameter holes 4, which are accurately spaced and of such 'diameter as to permit the insertion of the large diameter prongs of a vacuum tube, which project through the. base 2 into contact with the springs 9.

n the upper face of the base 2, I secure guide plate 1, which conforms in size and conternal guide for the prongs or studs of the tube tour to the base. In this plate, I provide a single large central hole5, which is so disposedthat its periphery is tangential to the prong holes. 3

and 4 at an outermost point of each of these latter holes.

.That is to say, the hole 5 circumscribes the holes 3-3 and 4-4, and hence is asuitable exto guide them for circumferential motion until they drop into register with the holes in base plate 2, as shown in Figure 4. 3 1

The plates 1 and 2 have symmetrically formed mounting ears disposed preferably diametrically and these ears have openings 6-6 formed ,therethrough. The holes.6-6 of the guide plate I register with like holes 6-6 in the Base plate 2. Mounting screws pass through holes 6-6 and serve to hold the socket upon a'suitable support and also to secure the plates 1-2 firmly together.

The insulator plate 1 serves two' purposea the .first of which is .to reenforce and strengthen the base 2. Preferably, the insulators 1 anjd. 2

, are made of a phenol-condensatiori product, such as Bakelite or Micarta-plate, although other suitable insulating materials may be substituted. The

base plate 2. which is relatively thin, is l'ilk forced by the plate 1; The second function performed by the plate 1 is that of guiding the prongs into their respective holes 3 and 4 in the base 2.

Also, the plate 1 covers the rivets 12-12 so that the connections to the socket may not be accidentally shorted or cross-connected.

et, little difllculty will be experienced in bring ing the prongs into registration with the hole '5. The tube is then rotated until the large di-' ameter prongs register with the holes 4, at which time the small diameter prongs will, of course register with the holes 3 and the prongs of the tube enter the socket by a movement at right angles to the plane of the base 2. r

The contacts 8 and 9 are, preferably, madeof sheet spring brass or bronze, although German silver or any other suitable spring material may be used. The contacts 9 are blanked out by the usual lanking die to provide the outline of the spring and tocut the slots llwith their sides substantially parallel, after which operation the slots'll are swedged tosmoothen their edges, and to form the bevelling of the corners at an angle to the face of the contact, which is to be brought into engagement with the tube. This can best be seen in Figure 6, wherein the beveled face is indicated at' 11'. The contacts are then formed to shape by the usual forming processes.

of the slot by the lateral pressure-of the body of no the spring.

The edges of slot 10 are likewise swedged to smoothen and form them at an angle to the abutting face of the contact.

The terminal end of the contact to which the connecting wires are to be attached is preferably tinned to permit ready soldering of wires to it.

terminal end is shown as containing two contacting end of the spring 9 outward towards the terminal end against the tension placed in 9 at the curved portion 19. The edges 11' of the slot 11, being bevelled, engage the tube prong 15 throughout a considerable length, thereby insuring a good, low resistance electrical. contact.

'I'he shape of the slot 11' is such thatthe tube socket. This gripping action of the spring 9 on the prongs of a tube or coil eliminates thepossibility 0! the l be being vibrated out of its socket and insures a permanent electrical contact to it, as long as it remains in the socket.

Each contact spring such as 9, shown in Fig. 7, comprises a body or base portion 16 which is provided with a central hole 17 by which it is secured as through the eyelet or rivet 12 upon the base 2. The ear 14 projects into a small hole formed in the base 2 and is forced tightly into the same by the clamping effect of the rivet 12 upon the base 16, so that the spring as a whole cannot rotate on the rivet 12. The rear part of the body has a connecting lug orterminal 8 rising therefrom, preferably at substantially right angles to the base 16, so that these terminals may lie substantially within the confines of the base plate 2.

The forward edge of the base 16 has the slotted contact member extending therefrom, this contact member comprising the inclined or diagonal portion 18 joined to the base 16 by a curved knee portion 19 and an outer reflex end portion 20. The slot 11 extends from within the fiat base portion 16 throughout the knee portion 19, the inclined contacting portion 18, to a point within the reflex or bent back end 20. The slot 11 is a closed parallel-sided slot, as can be seen from Figures 2, 3, 6 and '7, although in this specific modiflcation the edges of the slot are shown as beveled or chamfered,

When the studs such as 15 are inserted into the socket as shown in Figure 4 they are each guided longitudinally by the edges of the slots 11 and at the same time the studs spring back the inclined portions 18 which are the parts that really make contact with the studs. The curved knee portions 19 are flexed or bent to permit this. The diagonal or inclined contact making portion 18 is thus brought back substantially parallel to the stud and the edges of theslot 11 bear against the longitudinally extending parallel lines on the surface of the rodelike stud 15. Such lines are substantially parallel to the axis of the stud and since the stud is inserted or withdrawn axially, the tendency is to produce and maintain an excellent electrical contact which is not easily disturbed and and remains substantially permanent. The presentationof the two edges of the sheet metal spring tend to develop high unit pressures along the lines of engagement and this tends to scour or clear the two lines of contact on each stud.

The studs are guided initially by the holes 34 to limit them to axial movement. As soon as the studs enter betweenthe edges of the respective slots '1111 they are automatically centered by the springs themselves and resist any rota tional displacement of the tube which would tend to shift the lines of contact. The result is that the axial movement is'substantially fixed anti the scouring action of the two edges of the sheet metal presented to each stud is confined to longitudinally extending lines and the engagement between the parts does not tend to leave these lines. Any dirt or scale which might tend to become interposed will be cut away and displaced from the lines of contact. The slotting of the contact springs longitudinally also tends to permit some independent of action of the two contacting edges radially with respect to the center of the group. Also, a certain freedom .of spreading of the sides of the slot is present. This is particularly true because the main contacting part 18 is offset with respect to the closed ends'of the slot. These features are novel and highly advantageous.

Another important and advantageous feature of the contact spring of my invention resides in the fact that whatever wabbling or rocking may be imposed on the tube does not spoil the contact vides sufficient resiliency to permit a warping or twisting without permanent deformation of the springs. Also for rotary movement of the tube which may in slight degree be permitted by the holes 3-4 and which would tend to shift the studs 15 by motion of translation sidewise with respect to the contact springs does not in any way decrease or alter the contact because of the clutching action which the two lines of contact of the edges of each spring present to the stud. If the sidewise pressure of the studs be considered as releasing pressure on one edge it must be accompanied by increased pressure on the other edge. Hence, as soon as the rotating force is removed the tube tends to resume its position with the studs 15 centered in the slots 11 of the springs. The springs-all tend to center the corresponding studs with respect to their own slots and as a group they tend to center the group of studs by pressing towards the center of the group.

It will be obvious that, if the springs are disposed properly with respect to one another and to the prongs, the tube or coil will be positioned and securely gripped solely by the cooperative action of the springs and the edges of the perforations in the base will not be required to exert any positioning action upon the prongs. One of the advantages of such an arrangement is that the socket herein disclosed will operate satisfactorily if the springs are properly positioned with respect to the prongs even though the perforations are so much larger than their respective prongs as not to engage the prongs. .In this socket the perforation need serve only to guide the prongs into position.

Another of the advantages is that, since all of the springs cooperate with all of the-prongs in gripping and positioning the tube or coil, 'the forces of the springs on the prongs tend to equalize, and hence, a. substantially uniform contact pressure and consequently a uniform low contact resistance is obtained. This action is further improved, as pointed out elsewhere in this description, by the freedom of individual movement of the two portions of the spring adjacent the slot whereby they automatically adjust themselves to the surface of the prong.

It ordinarily is not necessary that the width of the slots which are to engage the two sizes of prong be different, but only that the width of the slots be less than the diameter of their respective prongs so that the corners of the slot edges engage the circumferences of the prongs contact more uniform, but there is less tendency to bite or score the prongs than where a sharp corner is provided. It will be obvious that this beveling is not essential to the principle invention.

The portion 20 of the-spring is reflexed or bent back so as to clear the outer end of the corresponding stud, which is often encumbered by the solder employedto secure electrical connection with the leading in.wires of the tube, and which solder causes lumps, or bulges to extend from the cylindrical surface of theend of the stud and which would, if: it were permitted to engage the spring, tend to interfere with proper contact thereby.

While I have shown a preferred embodiment in my invention, I have done so by way of example only as there are many modifications, which can be made by one skilled in the art without departing from the teachings of the invention. The four prong socket shown is for example only, as a five or more prong socket can be built within the teachings of my invention. Five prong sockets are in common use with modern alternating current vacuum tubes, and I am not, therefore, to be limited to the four-prong socket shown.

Having thus complied with the statutes and shown and described a preferred embodiment of my invention, what I consider new and desire to have protected by Letters Patent is pointed out in the appended. claims.

1. In combination, an electrical device having a plurality of prongs, and an electrical socket comprising a base containing a plurality of holes, a contact spring fastened to said base adjacent to each of said holes, said springs each having a portion projecting away from said base at an angle therefrom, a slot in each of said projecting portions extending entirely through said portion, a prong 01" said device projecting through the corresponding hole and resting tangentially against the edged the metal forming the slot, the edges of said slots per se engaging said prongs under the tension of said springs to hold the prongs in the socket and to establish an electrical connection therewith, the edges of the slots being held against spreading by integral portions of the springs.

'2. In combination, an electrical device having a plurality of prongs, and an electrical socket comprising a base containing a plurality of holes, a contact spring fastened to said base adjacent to each of said holes, said springs each having a portion projecting away from said base at an angle thereto,v a slot in said portion extending entirely through said portion, a prong of said device projecting through the corresponding hole and resting tangentially against the edge of the metal defining the slot, said prong moving said spring portion to increase the angle between it and said base'to thereby add tension to the spring, the edges-of said slot per se engaging and gripping said prong to hold it in the socket and to establish an electrical connection therewith, the edges of the slot of each spring being held against spreadingby an integral portion of the spring lying back of said edges and out of contact with the corresponding prong.

3. Asocket for an electrical device having cylindrical prongs comprising a base having a plurality of holes in it, a plurality of contact strips each of which has a foot.resting on the base through which-the contact is riveted to said base, a projection extending intoa hole in the base to lock the contact against rotation on said rivet, a terminal projecting from the outward end of said foot at substantiallyright angles to it and the base, acontact spring formed at an angle to said foot and disposedopposite and extending an-- gularly over one of the holes in said base, said spring being formed with a slot extending entirely through said spring and having a continuous periphery, and a guide plate attached to the opposite face of said base, said guide plate having a large hole circumscribing the holes in said base opposite which the contact springs are disposed, said guide plate hole guiding the cylindrical terminal prongs of the electrical device into registration with said holes in said base, through which said prongs project into engagement with the edges of the slots per se of said contact springs, said prongs moving said springs to in crease the angle made with the base and said edges engaging and gripping said prongs under the tension of said springs to hold the prongs in the socket and to establish an electrical connection therewith.

4. In a device of the class described, the combination of a base, said base having means for guiding a group of substantially parallel cylindrical rod-like contact studs endwise, contact springs of thin sheet metal having contact portions extending longitudinally along the rod-like contact studs and having integral laterally extending foot portions mounted on and secured to the base, said contact portions each having a slot extending entirely through said portion and presenting two longitudinally extending edges of the slot per se longitudinally against the cylindrical surface of the cooperating contact stud, said edges being spaced apart a distance less than the thickness of the stud to center the stud between them, integral parts of the contact spring holding the said sheet metal edges against spreading remote from the base, said springs pressing their pairs of longitudinal contact making edges toward the center of the group and thereby centering each of the contact studs between pairs of contact making edges and likewise tending to center the entire group independently of the guiding means of the base.

5. In a socket for a device having rod-like contact studs, the combination of a base, member comprising a plate formed of a thin sheet ofinsulating material having a plurality of guiding openings therethrough for guiding the rod-like contact studs, said plate being oblong to provide mounting ears with holes therethrough, thin sheet metal contact springs comprising flat base portions and integral contact portions, the base portions lying against the bottom side of the plate, fastening pins extending through the plate and the base portions for holding the springs with the contact portions in position to be engaged by the studs when they are projected endwise through the guiding holes, each of said contact portions having a slot extending entirely through said portion and presenting a pair of substantially parallel edges of the slot per se to the sides of the corresponding stud for providing substantially parallel lines of contact along the sides of its respective studs, said edges being maintained in' substantial parallelism by integral of the contact spring, each pair of said edges being spaced apart a distance less than the thickness of the contact studs and positioned to exert upon its respective prong a gripping force induced by the mutual cooperation of all of said pairs of edges and said prongs.

6. The combination with a device having cylindrical contact studs of a socket comprising a base member including a plate formed-of a thin sheet of insulating material, the central portion of the same having guiding edges for guiding cylindrical rod-like contact studs endwise, thin sheet metal contact springs each comprising a flat base portion, from the opposite ends of which project an longitudinally extending lines of contact by thecorresponding cylindrical contact stud when the stud is projected through the plate, the slots in the spring terminating short of the outer ends of the springs so that the end portions of said engaging edges are held against spreading, said springs being disposed to cause said edges to exert A a gripping action on said studs.

'7. In an electrical socket, in combination a base containing a plurality oi perforations, a contact 1 spring'secured to said base adjacent each of said perforations and. extending from said base in a positionto engage a prong extending through that perforation corresponding to the spring, each of said springs having a slot extending entirely through the spring and formed with a closed periphery and having longitudinally extending substantially parallel edges of the slot per se disposed to bear upon non-diametrically spaced portions 01' the circumference of the prong extending in the general direction ,of the axis of the prong to make substantially line contact with said prong.

8. In a socket for an electrical device having a plurality of mounting and conducting prongs, a base provided with a plurality of perforations to receive the prongs, a contact spring secured to and extending angularly from a point on said base adjacent each of said perforations, each of said springs having a' slot extending entirely through the spring and formed with a closed periphery and having two longitudinally extending edge portions in the slot per se, one corner of each slot edge engaging a prong of the device in opposition to a corner of the other slot edge, saidsprings being positioned relative to the prongs and to each other to exert a gripping action upon said prongs, and a centering action upon said device,

NEWTON C. SCHELLENGER...

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